yesterday i reloaded and shot 4 - 5 shot groups at 100 yards all were measured. i do believe these groups are better because i had the correct size dies" Custom Whidden dies " , before i was using my 6.5 Creedmoor dies with a .282 bushing in resizing bushing die and just a 6.5 seating die, i just felt these dies.were to loose for .257 caliber . with my new custom dies i used a .283 bushing in resizing die, with twice fired Lapua cases,Fed.205 primers, Reloader 17 in all groups > 1st 5 shot group with 131 gr. Black Jack bullets was 1/2 inch ,4 are in a 1/4 inch hole. , 2nd group with 131 gr.Black Jack bullets was 11/16 inch 4 are are a 1/4 inch hole. 3rd group was with 128 gr. Hammer bullets and i had to use .280 bushing in bushing resizer die to keep bullets tight in neck the group was poor 1 1/2 inch 5 shot group.
now this is the interesting part i had 7 shells that i had reloaded beforethat i had figured out how tight i needed necks to hold the hammer bullet firm started with .283 ended with .280 bushing in resizing die , all 7 of the different bushing size setup Hammer bullets in cartridge would turn but you could not push or pull them out so i decided to just shoot all 7 even if they all were a little different. those 7 loose bullets shot in a 3/4 group in a 1 inch square bulleye , so i decided too resize with the .283 bushing reload and shoot a group of 5 cartridges with these 128 gr. Hammer bullets ,seated them out a little more, dropped down 2 grs.of RL. 17 powder , i knew all 5 were loose and you could turn them but they would not pull or push in by hand these Hammer bullets have ring groves like Barnes bullets maybe that`s why they should have more neck pressure for hunting but this was for accuracy, so i shot these 5 loose Hammer bullet/cartridges and shot a 3/8 inch hole maybe a little less. so now i am wondering should i try a .284 bushing and loosen up the neck some for the 131 gr. Black Jack bullets ? i will also try the Hammer bullets more too , i will also say 131 gr. Black Jack bullets are now more consistent in group sizes with these custom Whidden dies, the method i seen on a video for using 6.5 Creedmoor dies is not the answer for reloading 257 Creedmoor ammo for accuracy you need 257 Creedmoor dies for a better cartridge to shoot.
Last edited by pete53; 01/08/21.
